At one time, the cable network was predominantly a vehicle for delivering entertainment. With the advent of the Internet and the rise in demand for broadband two-way access, the cable industry began to seek new ways of utilizing its existing plant. Pure coaxial (“coax”) cable networks were replaced with hybrid fiber networks (HFNs) using optical fiber from the head end to the demarcation with the subscriber coax (usually at a fiber node). Currently, a content-based network, a non-limiting example of which is a cable television network, may afford access to a variety of services besides television, for example, broadband Internet access, telephone service, and the like. The existing cable network topology was originally optimized for downstream (toward the subscriber) only service. New equipment was added to the network to provide two-way communication.
One example of a service that may be implemented in a variety of contexts, including over a content-based network that also offers data services, is Internet telephony, including Voice over Internet Protocol (VoIP), optionally with video and/or instant messaging. A non-limiting example is the SKYPE® service (registered mark of Skype Corporation, Dublin, Ireland).